The object of this research project is to extend the usefulness of circular dichroism (CD) and other optical spectroscopic techniques in the study of protein structure. One area of interest is the conformation of polypeptides with aromatic side-chains. The coil-helix transition recently observed in dimethylsulfoxide/dichloroacetic acid solutions of poly-L-tyrosine will be further explored and similar transitions will be sought in poly-beta-benzyl-L-aspartate, poly-L-phenylalanine, etc. The interaction of coenzymes (NADH, NAD, pyridoxal) and prosthetic groups (heme, flavin) with proteins will be further explored by both experimental and theoretical methods. The binding of di- and triphenylmethyl dyes to enzyme active sites, especially in NAD-dependent dehydrogenases, will be studied extensively. These CD probes can potentially be used for comparing active sites of related enzymes, for obtaining information about the active site environment and conformation, and for detecting conformational changes upon binding coenzyme or effectors. Chromium nucleotides should prove very useful for probing the active sites of kinases and other ATP- and ADP-binding proteins. We will attempt to resolve the tridentate CrATP complex into its optical isomers by affinity chromatography and use these to determine the stereochemistry of ATP-binding sites.